Rotating driving unit

ABSTRACT

The invention relates to a rotary drive for a tool holding device with a shaft for bearing the holding device where the rotary drive performs both machining and milling using a common tool changing device. The inventor has a first hollow shaft ( 7 ) arranged concentrically to a shaft ( 1 ), the hollow shaft being driven by means of a drive device. Between the shaft ( 1 ) and the hollow shaft ( 7 ) and engageable and disengageable coupling ( 15  and  16 ) is arranged, which can. be operated by relative movement of the shaft ( 1 ) and the first hollow shaft ( 7 ). Between the shaft ( 1 ) and the first hollow shaft ( 7 ) a second hollow shaft ( 12 ) is arranged to cause such relative axial movement and rotatably bear the shaft ( 1 ). The first hollow shaft ( 7 ) is rotatably supported in a housing ( 5 ). Between the first hollow shaft ( 7 ) and the second hollow shaft ( 12 ) a gripping device is arranged, which couples with the second hollow shaft ( 12 ) when hollow shaft ( 7 ) is driven.

CROSS REFERENCE TO RELATED APPLICATION

The present application is the national stage under 35 U.S.C. 371 ofPCT/EP98/05689, filed Sep. 8, 1998.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The invention relates to a rotary drive for a tool holding device inaccordance with the preamble of claim 1 herein.

2. Prior Art

Tool drives for lathes have to fulfill the requirement of operating at arelatively high speed of rotation and a relatively low torque. Tooldrives for milling machines on the contrary have to fulfill the oppositerequirement, i.e. operating at a relatively high torque and a low speedof rotation. In the case of machining centers, which combine a lathe anda milling machine, separate drives with separate tool changing devicesare consequently provided for machining by turning and machining andmilling.

OBJECT AND SUMMARY OF THE INVENTION

There is a need for a rotary drive which renders possible both machiningby turning and machining by milling.

This object is to be achieved by the invention as described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

One working embodiment will now be described in the following withreference to the drawing, same showing a section taken through the toppart of a rotary drive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

At its right hand end a shaft 1 bears an attachment flange 2, which forits part bears a tool holding device 3. On the left hand end of theshaft 1 a hollow shaft stub 4 is arranged, which is engaged by a drivedevice, something which is diagrammatically as indicated by the arrow 8.In the axial setting of the shaft 1 indicated the shaft 1 is uncoupledfrom the shaft stub 4.

By means of bearings 6 a housing 5 rotatably carries a hollow shaft 7.This hollow shaft 7 bears a worm wheel 9, which is in mesh with a worm10. This worm 10 is rotatably borne by the housing 5 and is driven by afurther drive device, not illustrated,. In the interior of the hollowshaft 7 a gripping quill 11 is arranged, which rotates with the hollowshaft 7. The gripping quill 11 surrounds a further hollow shaft 12,which by means of bearings 13 rotatably supports the shaft 1. Thefurther hollow shaft 12 and the shaft 1 are able to be shifted jointlyin the axial direction.

A flange 14 on the shaft 1 bears planar splines 15 which engage planarsplines 16 on the right hand end of the hollow shaft 7.

The left hand end of the further hollow shaft 12 is designed in the formof a double acting cylinder 17, whose chambers are delimited by thehollow shaft 7. The hollow shaft 7 bears a brake disk 18 whichcooperates with a brake pad 19 on the housing.

For the performance of machining by milling the shaft 1 and the hollowshaft 12 assume the axial setting indicated in the figure. In this casethe splines 15 and 16 are in mesh with each other. The chamber 20 insidethe gripping quill 11 is acted upon by pressure, and the chamber on theright of the cylinder 17 also. The shaft 1 and the shaft stub 4 areuncoupled from each other. If the worm 10 is caused to rotate, theattachment flange 2 will turn as well and consequently the tool holdingdevice 3 as well relatively slowly, but with a high torque. The shaft 1,the hollow shaft 12 and the shaft 7 will rotate jointly, the grippingquill 11 being responsible for gripping engagement between the twohollow shafts 7 and 12. If the worm 10 is halted, the brake pad 19 orjaw will come into engagement with the brake disk 18. The shafts arerotatably carried by the bearings 6.

If machining by turning is to be performed, the worm is halted. Thechamber on the left of the cylinder 17 is put under pressure, whereasthe right hand chamber, like the chamber 20, is relieved of pressure. Asa result the further hollow shaft 12 will perform an axial movement tothe right. Since the further hollow shaft 12 is connected with the shaft1 in an axially movable manner via the bearings 13, the shaft 1 willperform the same axial movement. The splines 15 and 16 come out ofengagement with each other, whereas the shaft 1 is connected with theshaft stub 4 for the transmission of rotary force. If now the drive 8 isoperated, the attachment flange 2 and the tool holding device 3 willrotate at a relatively high speed so that turning operations, i.e.machining by turning, are possible. When the hollow shaft 7 is notrotating, the brake pad 19 is applied to the brake disk 18.

For the supply of the chambers on either side of the cylinder 17 and thechamber 20, the hollow shaft 7 possesses a hollow shaft head 21, whichwith the aid of bearings 22 rotatably supports the shaft stub 4 and issurrounded by a head 23 on the housing, such head cooperating with theshaft head 21 like a slip ring and has hydraulic ports. Such ports areconnected via hydraulic connections 24 with the above mentionedchambers.

What is claimed is:
 1. A rotary drive for a tool holding device (3)comprising: a shaft (1) adapted to bear the holding device (3); a firsthollow shaft (7) arranged concentrically over the shaft (1); the firsthollow shaft adapted to be driven by means of a drive device; anengageable and disengageable coupling (15, 16) arranged between theshaft (1) and the first hollow shaft (7); the coupling operated byrelative axial movement between the shaft (1) and the first hollow shaft(7); a second hollow shaft (12) arranged between the shaft (1) and thefirst hollow shaft, adapted to cause the relative axial movement and torotatably bear the shaft (1); the first hollow shaft (7) rotatablysupported in a housing (5); a gripping device arranged between the firsthollow shaft (7) which when the hollow shaft (7) is driven couples withthe second hollow shaft (12); and wherein the first hollow shaft (7) isrotatably mounted in the housing (5) in a manner preventing axialmovement when the second hollow shaft (12) axially shifts the shaft (1).2. The rotary drive as claimed in claim 1, characterized in that betweenthe first hollow shaft (7) and the housing (5) a brake (18 and 19) isprovided, which to operates when the first hollow shaft (7) is notrotating.
 3. The rotary drive as claimed in claim 1, characterized inthat the first hollow shaft (7) and the second hollow shaft (12) aredesigned in the form of a double acting piston.
 4. The rotary drive asclaimed in claim 1, characterized in that the part, adjacent to thesecond hollow shaft (12), of the first hollow shaft (7) is designed inthe form of a hydraulically operated gripping quill (11).
 5. The rotarydrive as claimed in claim 4, characterized in that a shaft head (21) onthe first hollow shaft (7) and a housing head (23) cooperate in themanner of a slip ring arrangement and have the hydraulic connections tothe double acting piston and the gripping quill (11).
 6. The rotarydrive as claimed in claim 5, characterized in that the head (21) on thefirst hollow shaft (7) rotatably supports a shaft stub (4) able to becoupled with the shaft (1), such shaft stub (4) being coupled with theshaft (1) in one axial setting thereof and in another axial settingthereof being uncoupled from the shaft (1) and being acted upon by adrive device (8).
 7. A rotary drive for a tool holding device (3)comprising: a shaft (1) adapted to bear the holding device (3); a firsthollow shaft (7) arranged concentrically over the shaft (1); the firsthollow shaft adapted to be driven by means of a drive device; anengageable and disengageable coupling (15, 16) arranged between theshaft (1) and the first hollow shaft (7); the coupling operated byrelative axial movement between the shaft (1) and the first hollow shaft(7); a second hollow shaft (12) arranged between the shaft (1) and thefirst hollow shaft, adapted to cause the relative axial movement and torotatably bear the shaft (1); the first hollow shaft (7) rotatablysupported in a housing (5); a gripping device arranged between the firsthollow shaft (7) which, when the hollow shaft (7) is driven, coupleswith the second hollow shaft (12); wherein the first hollow shaft (7) isrotatably mounted in the housing (5) in a manner preventing axialmovement when the second hollow shaft (12) axially shifts the shaft (1)and, a brake (18 and 19) arranged between the first hollow shaft (7) andthe housing (5) which operates when the first hollow shaft (7) is notrotating.
 8. The rotary drive as claimed in claim 7 wherein, the firsthollow shaft (7) and the second hollow shaft (12) are designed in theform of a double acting piston.
 9. A rotary drive for a tool holdingdevice (3) comprising: a shaft (1) adapted to bear the holding device(3); a first hollow shaft (7) arranged concentrically over the shaft(1); the first hollow shaft adapted to be driven by means of a drivedevice; an engageable and disengageable coupling (15, 16) arrangedbetween the shaft (1) and the first hollow shaft (7); the couplingoperated by relative axial movement between the shaft (1) and the firsthollow shaft (7); a second hollow shaft (12) arranged between the shaft(1) and the first hollow shaft, adapted to cause the relative axialmovement and to rotatably bear the shaft (1); the first hollow shaft (7)rotatably supported in a housing (5); a gripping device arranged betweenthe first hollow shaft (7) which, when the hollow shaft (7) is driven,couples with the second hollow shaft (12); wherein the first hollowshaft (7) is rotatably mounted in the housing (5) in a manner preventingaxial movement when the second hollow shaft (12) axially shifts theshaft (1), and wherein, adjacent to the second hollow shaft (12), thefirst hollow shaft (7) is designed in the form of a hydraulicallyoperated gripping quill (11).
 10. The rotary drive as claimed in claim9, wherein, a shaft head (21) on the first hollow shaft (7) and ahousing head (23) cooperate in the manner of a slip ring arrangement andhave hydraulic connections to the double acting piston and the grippingquill (11).
 11. The rotary drive as claimed in claim 9, wherein the head(21) on the first hollow shaft (7) rotatably supports a shaft stub (4)which can be coupled with the shaft (1), the shaft stub (4) beingcoupled with the shaft (1) in one axial setting of the shaft (1) and inanother axial setting of the shaft (1) being uncoupled from the shaftand being acted up on by a drive device (8).